It is recommended to recite Suratal-Kahf completely the night before Friday, and it is also recommended to do so Friday itself, before Maghrib time. Ibn Abidin said, And it is best to do so early on Friday, in order to rush to the good and to avoid forgetting. [Ibn Abidin, Radd al-Muhtar, Bab al-Jumu`a]

The evidence for it being recommended includes the hadith related by Hakim and Bayhaqi, from Abu Sa`id (Allah be pleased with him), Whoever recites Surat al-Kahf on Friday, light shall shine forth for him between the two Fridays. [Ibn Hajar, Talkhis al-Habir]

It is mentioned in Heavenly Ornaments, by Imam al-Tahanawi:

The Virtues of Jumu’ah

1 . Rasulullah (Allah bless him & give him peace) said: “Friday is the best of days. It was on this day that Hadrat Aadam alayhis salaam was created, it was on this day that he was granted entry into jannah, it was on this day that he was removed from jannah (which became the cause for man’s existence in this universe, and which is a great blessing), and the day of resurrection will also take place on this day. ” (Sahih Muslim)

2 . It is related from Imam Ahmad rahmatullahialayh that he said that in certain aspects the rank of the night of jumu’ah is even higher than Laylatul Qadr One of the reasons for this is that it was on this night that Rasulullah (Allah bless him & give him peace) appeared in the womb of his mother Rasulullah’s (Allah bless him & give him peace) appearance in this world was a cause of so much good and blessings both in this world and in the hereafter that they cannot be enumerated. (Ash’atulLama’aat)

3 . Rasulullah (Allah bless him & give him peace) said: “There is such an hour on Friday that if any Muslim makes dua in it, his dua will definitely be accepted. ” (Bukhari, Muslim) The ulama have differed in specifying that hour which has been mentioned in the Hadith . Shaykh Abdul Haq Muhaddith Dehlawi rahmatullahialayh has mentioned 40 different opinions in his book Sharh Sifrus Sa’aadah . However, from among all these opinions he has given preference to two opinions: (1) That time is from the commencement of the khutbah till the end of the salaat, (2) That time is towards the end of the day . A big group of ulama have given preference to this second opinion and there are many Ahadith which support this opinion . Shaykh Dehlawi rahmatullahialayh says that this narration is correct that Hadrat Fatimah radiallahuanha used to order her maid on Fridays to inform her when the day is about to end so that she could occupy herself in making zikr and duas. (Ash’atulLama’aat)